In moulding chambers for mould-string plants of this kind it is known to provide variable sizes of the moulding chamber by making the side walls of the moulding chamber movable and adjusting the positioning of the side walls by means of a hydraulic system. A moulding chamber of this type is known from EP 1 149 645 A1. A problem with a moulding chamber of this type is that it is not possible to use pattern plates that vary in the height.
Furthermore, WO 2009/074838 discloses a moulding chamber arrangement for a mould-string plant, in which a variable size of the moulding chamber is provided by using adaptor plates for reducing the size of the moulding chamber. In connection with reduction of the height of the moulding chamber, the insertion of an adaptor plate on the upper wall of the moulding chamber increases the distance between the sand feed system and the moulding chamber, whereby the sand flow into the moulding chamber will be affected unfavourably. Moreover, it is very laborious and time consuming to insert or remove adaptor plates in the chamber ceiling because it requires the movement of very heavy components (adaptor plates of the above mentioned kind weigh several hundreds of kg), and inevitable residue deposits of sand in the sand feed system will also leak into the moulding chamber during the insertion or removal of the adaptor plates.
Additionally, FR 2 196 865 discloses a sand moulding machine wherein sand moulds are formed by pressing pattern plates toward each other. After the sand moulds are formed the top plate is raised so that the sidewalls can tilt slightly and therefore not stick to the sand mould when it is being expelled from the form chamber. Thus, even though the top plate is movable vertically, the form chamber in which the sand moulds are formed is not altered in size, and therefore in particular not in the vertical direction. Accordingly, the volume of the form chamber is not altered.
U.S. Pat. No. 3,654,986 discloses a type of sand moulding machines that operates according to the so-called match plate principle, which employs match plates and flasks. The disclosed machine is equipped with a height adjustable receiver table, which receives the finished moulds and levels them with a conveyor. The moulding chamber itself is not changed in size by the movement of the receiver table.